Previous studies in nonprimates suggest that androgen-regulated epididymal secretory proteins are important for sperm maturation. However, little is known about androgen-regulation of epididymal function in primates. Our studies in the intact chimpanzee indicate that epididymal lumenal proteins interact with the surface of sperm and effect their fertilizing capacity. However, the androgen dependence of these epididymal proteins and their biological role in sperm maturation are unknown. In the studies described in this application, we propose: 1. to define the pattern and duration of spermatogenesis and determine the epididymal transit time in the chimpanzee: To use intact male chimpanzees under conditions of reversible chemical hypophysectomy and castration: 2. to identify androgen dependent event which effect the fertilizing capacity of epididymal sperm and to localize their origin to the caput region and/or to the cauda region of the chimpanzee epididymis; and. 3. to identify androgen-dependent secretory proteins in the epididymal microenvironment and to determine which of these interact with sperm to modify their fertilizing capacity. Achievement of these specific aims will provide significant information on androgen control of epididymal function and of sperm maturation in a primate species. Such information can provide a valuable approach to the development of clinical methods both for the reduction of fertility and for the alleviation of infertility by manipulation of epididymal microenvironment.